An endoscope is an instrument which enables a physician to view inaccessible regions within a patient's body. A conventional endoscope may include, for example, an elongated flexible endoscope body and optical components carried by the endoscope body to enable viewing of an interior body region of a patient. The optical components may include, for example, an illumination fiber for illuminating a region to be viewed, an eyepiece and image fibers which transmit an image proximally to the eyepiece.
It is also known to provide an endoscope which has a distal region which is more flexible than a proximal region. The greater stiffness of the proximal region may be the result of reinforcing the proximal region of the endoscope body with, for example, a wire braid.
It is known to provide an endoscope body which includes a polyimide material. Although polyimide provides excellent protection for the optical components within the endoscope body, it does reduce the overall flexibility of the endoscope and may not be as lubricous as desired. Endoscope bodies constructed of polytetrafluoroethylene have the desired lubricity but are generally difficult to bond to other components.
In order for an endoscope to gain access to an interior body region, it often necessary or desirable to pass the endoscope through a catheter, and in some situations, the clearance between the endoscope and the lumen of the catheter through which the endoscope is passed is minimal. This tends to create significant surface area for sliding contact between the endoscope and the catheter thereby making the endoscope more difficult to move relative to the catheter. In addition, it is sometimes necessary or desirable to introduce a liquid, such as a flush solution, through the lumen of the catheter and around the endoscope. The existence of a very small clearance between the endoscope and the catheter makes this task difficult.
It is sometimes desirable to use an endoscope with an everting catheter. An everting catheter typically includes an outer catheter having an outer catheter lumen, an inner catheter movable longitudinally in the outer catheter lumen and having an inner catheter lumen and an everting element coupled to the outer catheter and to the inner catheter. By applying fluid pressure to the everting element and by moving the inner catheter distally in the outer catheter lumen, the everting element can be everted through a distal opening of the outer catheter. The everting element may form an extension of the inner catheter lumen.
The endoscope is positioned within the inner catheter lumen and the extension of the inner catheter lumen. With the instrument so positioned, pressurizing of the everting element causes the everting element to grip a region of the instrument.
This gripping of the instrument by the everting element is useful in that the eversion process may be used to cause the everting element to pull the instrument into the desired body region. Unfortunately, this gripping action is also undesirable to the extent that the physician wishes to move the instrument independently of, and relative to, the everting element.
Parent application Ser. No. 780,871 discloses a method and apparatus which enables the instrument to be moved relative to the everting element of the everting catheter system which includes introducing a flush solution between the everting element and the instrument where the everting element grips the instrument. This frees the instrument from the gripping action of the everting element so the instrument can be moved relative to the everting element. For example, the flush solution can be introduced to a preformed flow passage, i.e. a flow passage that exists even when the everting element grips the instrument. This assures that the flush solution can more easily pass between the everting element and the instrument.